Vaporizer apparatus for vapor deposition equipment

ABSTRACT

An elongated vaporizer, which may be a longitudinal wire, is mounted on a parallel current bus aligned near the axis of the vapor deposition vacuum vessel. Two or more such combinations provided in a vapor deposition vessel are arranged to lie in a vertical plane and collecting pans are mounted on each current bus beneath each vaporizer. A glow discharge electrode is also mounted in this vertical plane. Heating current is applied to one end of each vaporizer by an insulated lead. The other end of the vaporizer is connected rigidly to the supporting bus which is grounded to the vessel wall. The vertical arrangement in one plane makes possible a wide effective angle over which vapor deposition is effective.

United States Patent Kerner 1 Nov. 11, 1975 15 VAPORIZER APPARATUS FORVAPOR 3.598.957 8/1971 Yasuda et a1. 219/271 DEPOSITION EQUIPMENT3.637.980 1/1972 Fox et a1 219/275 X 3.698.946 10/1972 Kaspaul et al.117/107 X Inventor: Karl Kernel, Stuttgart, Germany 3.715.234 2/1973 sum117/107 x [73] Assignee: Robert Bosch G.m.b.H., Stuttgart,

Germa y Primary Examiner-C. L. Albritton Filed: Jan. 1974 Alto/me Agent.01 FumlFlynn & Frishauf An elongated vaporizer, which may be alongitudinal [30] Forelgn Apphcauon Pnomy Data wire, is mounted on aparallel current bus aligned near Feb. 24. 1973 Germany 2309405 the axisof the vapor deposition vacuum vessel, Two

' or more such combinations provided in a vapor depo- 1 l 9/2 1 18/491;219/275 sition vessel are arranged to lie in a vertical plane and Int.Cl.2 conecting pans are mounted on each urrent bus be- 1 Field 05 ch 21/271, 2 118/48, neath each vaporizer. A glow discharge electrode is 149-1, 1 107-1 also mounted in this vertical plane. Heating current isapplied to one end of each vaporizer by an insulated 1 1 ReferencesCited lead. The other end of the vaporizer is connected rig- UNITEDSTATES PATENTS idly to the supporting bus which is grounded to the2.339.613 1/1944 Becker et a1 118/49 x Vessel Wall The Verticalalrangeme"t one P111e 2.373.823 4/1945 Gold 118/49 x makes Possible 11Wide effective angle Over which 3.015.587 1/1962 MacDonald 118/49 x p rpo iti n is ffective. 3.068.337 12/1962 Kuebrich et a1. 219/275 X3.246.626 4/1966 Betar 118/49 8 Clams, 7 Drawmg Flgures U.S. Patent Nov.11,1975 Sheet1of2 3,919,525

Fig.1 Fig.2

PRIOR ART US. Patent Nov. 11,1975 Sheet20f2 3,919,525

VAPORIZER APPARATUS FOR VAPOR DEPOSITION EQUIPMENT This inventionrelates to vaporizing apparatus for use in the high vacuum vapordeposition process for depositing vaporizable material in layerscovering a relatively large area.

The vaporizing apparatus, which forms the actual source of the vapor invapor deposition equipment, consists either of a row of smallerVaporizers, usually in spiral shape or in the form of vaporizing boats,or else consists of a vaporizer wire running more or less along the axisof an elongated vacuum vessel. If two or more different layers are to bevapor deposited, a second and other additional vapor depositionapparatus can be disposed parallel to the first in the same vessel.

The known vaporizing apparatus for vapor deposition equipment have anumber of disadvantages. The usable solid angle in which the vaporizeris effective is relatively small because of unfavorable geometry of thearrangement and, furthermore, when two or more vaporizers for differentmaterials are provided in a vessel, theydeposit material on each other.

It is an object of the invention to provide a vaporizing apparatus forvapor deposition equipment which with a simple construction arrangementwill provide a wide solid angle of effectiveness of vapor transfer andwill be reliable in operation. It is a further object of the inventionto provide vapor deposition apparatus including a plurality ofVaporizers for different materials in which vapor deposition on the idlevaporizer or Vaporizers is largely eliminated.

SUBJECT MATTER OF THE PRESENT INVENTION Briefly, both the vaporizerelements and the electric current leads necessary for their currentsupply are disposed parallel to the axis of the vacuum vessel used forvapor deposition and they are arranged to lie substantially in the sameplane. In a particularly advantageous arrangement, the plane in whichthe vaporizing means and their current leads are located is a verticalplane. The vertical arrangement has the advantage that without theprovision of additional supporting members and without reduction of thesolid angle of vapor transfer a drip pan for catching loosenedvaporizing material dropping off the vaporizer can also be provided inthe same plane, preferably mounted on a current lead beneath thevaporizer.

The longitudinal wire typefof vaporizer element is preferred for theabove-described apparatus because in this case the effective solidangle, including all the directions in which direct vapor transfer takesplace, is the largest. In both cases in which a glow discharge is usedfor cleaning the vessel, the glow discharge electrode can advantageouslybe aligned in the same plane, preferably a vertical plane, in which thevaporizer and its current lead, or two or more of each, lie.

If the vapor deposition equipment requires two or more separatevaporizers, it is desirable in many cases to provide a baffle by whichat least one of the vaporizers can be covered or screened off. In aparticularly useful arrangement, the baffle is mounted so that it can beswung so as to cover selectively either one of two vaporizers.

The invention is further described by way of example with reference tothe accompanying drawings, in which:

FIG. 1 is a diagrammatic perspective view of a cylindrical vessel withspiral type vaporizing apparatus, as known in the prior art;

FIG. 2 is a diagrammatic perspective view of a cylindrical vessel with awire type vaporizing apparatus aligned near the vessel axis, as known inthe prior art;

FIG. 3 is a diagrammatic perspective view of a cylindrical vesslprovided with two parallel wire type vaporizers, as known in the priorart;

FIG. 4 is a diagrammatic cross-section of vaporizer apparatus in avacuum vessel corresponding to FIG. 3;

FIG. 5 is a diagrammatic cross-section of vaporizing apparatus accordingto the invention in a cylindrical vacuum vessel;

FIG. 6 is a longitudinal view, mostly in section, of a vaporizerapparatus in accordance with the invention; and

FIG. 7 is a diagrammatic cross-section showing the principle ofconstruction of a longitudinal wire multiple vaporizer according to theinvention provided with pivoted baffles.

FIGS. 1 to 3 shown known forms of vaporizer apparatus in vapordeposition equipment, in a diagrammtic fashion, FIG. 1 showing avaporizing apparatus composed of a number of spiral shaped Vaporizers,FIG. 2 a longitudinal wire vaporizer aligned near the axis of the vacuumvessel and FIG. 3 two parallel longitudinal wire Vaporizers. Thearrangement of FIG. 3 is used if two or more different layers are to bevapor deposited.

It is generally desired to deposit layers of even depth over large areaswith metals and/or dielectric materials by means of industrial vapordeposition equipment of this kind. The vaporizing apparatus in thisequipment, as indicated in FIGS. 1 to 3, generally utilize ahorizontally disposed cylindrical vacuum vessel evacuated to about 10"to 10 torr. The vaporizer apparatus of such vapor deposition equipmentis generally located in the neighborhood of the cylinder axis. Thearticles to be coated by vapor deposition can, for example, be mountedon a drum (not shown) by which they can be moved circumferentially alongthe inner wall of the vacuum vessel. Better results are obtained bymeans (not shown) providing a planetary movement of the articles to becoated, in which case there is, in addition to the circular movementalong the vacuum vessel wall, a rotation of the articles being coated ontheir own axes.

FIG. 4 shows a known form of vaporizing apparatus with two longitudinalvaporizer wires 10 and 11 lying in a horizontal plane passing close tothe axis of the vacuum vessel. Beneath the vaporizer wires 10 and 11 isa drip pan 12, below which are three current supply busses 13, 14 and15. Still further below is a glow discharge electrode 16. The glowdischarge electrode consists of the electrode proper 17 and a shieldstructure 18 that is electrically and mechanically connected to thegrounded current supply bus 15 on which the drip pan 12 is alsosupported. The current bus 13 delivers the current for the vaporizerwire 10, while the current bus 14 provides the current for the vaporizerwire 11.

The usable solid angle, more particularly the usable cross-sectionalangle, the angle a for the wire 10 and the angle b for the wire 11, isrelatively small and amounts to only a little over In the lower portionof the vacuum vessel 19 there is produced practically no vapordeposition and the obtainable layer thickness is limited both for thisreason and on account of the limited capacity of the vaporizer wires forvapor deposition on the articles, particularly in the case of articlesof considerable areas. Furthermore, in this type of arrangement the twoVaporizers I and 11 deposit material on each other, which can beprevented only by a supplementary baffle which would still furtherreduce theusuable cross-sectional angle of effective vapor deposition.

. In FIG. the vacuum vessel is again designated 19. Inside the vessel inthis case are a first vaporizer wire 20, a first current lead or bus 21,a second vaporizer wire 22, a second current lead or bus 23 and a glowdischarge electrode 24, all arranged vertically one below chargeelectrode 24. In order to simplify the diagram,

the representation of drip pans has been omitted, but it will beunderstood that these could rest on the upper surfaces of the busses 21and 23, respectively.

By arranging the two wire type vaporizing devices and the current supplybussesin one plane, there is obtained, as is clearly to be recognizedfrom FIG. 5, a substantial increase of the usable cross-sectional angledefining all the directions in which direct vapor transport fordeposition is possible. This angle for both of the two vapor depositionapparatuses shown in FIG. 5 can amount to nearly 360. In FIG. 5, thisangle for the vaporizer wire is designated a and the angle for thesecond vaporizer wire 22 is composed of two sectors each designated B/2.These angles shown in crosssection of course define solid angles betweentwo radial planes meeting on the axis of the vaporizer wire.

FIG. 6 shows a longitudinal section of the vaporizing apparatus of thevapor deposition equipment. An end wall 26 of the vessel 19 is shown,but otherwise the structure of the vessel 19 has been omitted forsimplicity. Openings 27 and 28 are provided in the end wall 26 toprovide an insulated feed-through andsupport for the leads 29 and 30through which theelectric supply voltage is furnished to the Vaporizers.Flexible current leads 31 and 32 are connected to the leads 29 and 30,respectively, and are connected at their other ends with clampingterminals 33 and 34, respectively, which are mounted with springstending to stretch the vaporizer wires 20 and 22 that are clamped in theclamping terminals 33 and 34. The other ends of the vaporizer wires 21and 22 are respectively held in fixed clamping terminals 35 and 36 thatare grounded to the vacuumvessel structure through the grounded currentbusses 21 and 23 to which the post 37 on which they are mounted isfastened. The current supply leads 21 and 23 are rigid members alsoserving for mechanical support of the post 37 and the vaporizer wiresand they are at ground plane results in an increased useful anglethrough which vapor deposition takes place, as well as a form ofconstruction in which the drip pans are readily providedQsince they maybe simply carried on top of the current supply busses 21 and 23.

From FIG. 7 it will be seen how either one of the two vaporizing meansof FIG. 5 and FIG. 6 can be selectively covered or screened off by abaffle means 40. This baffle means is composed of two halves 41 and 42,each having an L-shaped cross-section, mounted on axes passing throughthe points 43 and 44, so as to selectively cover one of the twovaporizing devices 20, 21 and 22, 23. In FIG. 6 the baffle means 40 wasleft out so that the structure inside could be better shown.

Instead of Vaporizers in' longitudinal wire form, it is of coursepossible to utilize vaporizers otherwise constructed, but, generally,other types of arrangements will involve complication in constructionand increase of expense. It is nevertheless readily conceivable that thevaporizing apparatus instead of having one or two longitudinal vaporizerwires, could have one or two rows of spiral Vaporizers or vaporizingboats for vaporizing the material to be vaporized. In a verticalarrangement, both vaporizing boats and spiral vaporizer elements, aswell as a longitudinal wire, are well suited for use as the uppervaporizer, but for the lower vaporizer only a row of spirals or alongitudinal wire come into question, and the alternative of a row ofvaporizing boats practically drops out of consideration, since it doesnot vaporize well downwards and in the lower position would also besubject to some blocking out by the upper vaporizer apparatus. Althoughthe longitudinal wire form is preferred in a general way, the use ofspiral elements or vaporizing boats can be advantageous in particularcases for vapor depositing layers of certain materials.

The term solid angle has been used to indicate angular spread ofdivergence in space in accordance with the usage in solid geometry.Space angle, divergence angle or angle of diffusion are equivalentterms. In the case of diffusion from a line source, the cross-sectionalor sectoral angle determines the spread of rectilinear vapor diffusionpaths, and hence the extent of direct vapor diffusion from vaporizer toexposed substrates.

Although the invention has been described with reference to particularillustrated embodiments, it will be understood that variations andmodifications are possi ble within the inventive concept.

I claim:

1. In an elongated vapor deposition high vacuum vessel, a vaporizerapparatus comprising at least two elongated vaporizing means capable ofbeing heated by the passage of electric current therethrough (20, 22)and an elongated current return lead for each of said vaporizing means(21, 23), said vaporizing means and said current return leads beingdisposed parallel to the direction in which said vessel is elongagtedand lying substantially in one plane.

2. Vaporizing apparatus as defined in claim 1 in which said vaporizingmeans (20, 22) and said current return leads (2 1, 23) lie substantiallyin a vertical plane and in which, further, elongated drip pan means (38,39) are longitudinally disposed beneath each vaporizing means forsubstantially the full length thereof between the vaporizing means andits current return lead.

3. Vaporizing apparatus as defined in claim 1, in

which said vaporizing means are constituted in the form of straightlongitudinal wires (20, 22).

4. Vaporizing apparatus as defined in claim 2 in which there are twosets of a vaporizing means and a current lead disposed one above theother, each of said current leads (21, 23) of one of said sets beingdisposed beneath the vaporizing means of the set.

5. Vaporizing apparatus as defined in claim 4, in which one drip panmeans (38, 39) is affixed on top of each of said current leads (21, 23)beneath one of said vaporizing means (20, 22).

6. Vaporizing apparatus as defined in claim 1, in which an elongatedplanar glow discharge electrode (24) is provided disposed edgewisebeneath the lowermost of said current return leads substantially in thesame plane as said vaporizing means (20, 22) and said current returnleads (21, 23), in which further at least said lowermost of said currentreturn leads has an end at ground potential and in which a substantiallygrounded electrode (25) spaced from and covering one side of said glowdischarge electrode is disposed extending downward from said lowermostcurrent return lead.

7. Vaporizing apparatus as defined in claim 4, in which baffle means(40) for screening off said vaporizing means are mounted in such a wayas to be capable 'to said respective current return leads (21, 23) forholding one end of each vaporizing means and in which, further, springtensioned clamping terminals (33, 34) are provided for the other ends ofsaid vaporizing means and are insulatedly supported by said currentreturn leads (21, 23) so as to exert tension on said vaporizing means,said spring tensioned clamping terminals being connected by flexibleconductors (31, 32)

to a supply voltage source.

1. In an elongated vapor deposition high vacuum vessel, a vaporizerapparatus comprising at least two elongated vaporizing means capable ofbeing heated by the passage of electric current therethrough (20, 22)and an elongated current return lead for each of said vaporizing means(21, 23), said vaporizing means and said current return leads beingdisposed parallel to the direction in which said vessel is elongagtedand lying substantially in one plane.
 2. Vaporizing apparatus as definedin claim 1 in which said vaporizing means (20, 22) and said currentreturn leads (21, 23) lie substantially in a vertical plane and inwhich, further, elongated drip pan means (38, 39) are longitudinallydisposed beneath each vaporizing means for substantially the full lengththereof between the vaporizing means and its current return lead. 3.Vaporizing apparatus as defined in claim 1, in which said vaporizingmeans are constituted in the form of straight longitudinal wires (20,22).
 4. Vaporizing apparatus as defined in claim 2 in which there aretwo sets of a vaporizing means and a current lead disposed one above theother, each of said current leads (21, 23) of one of said sets beingdisposed beneath the vaporizing means of the set.
 5. Vaporizingapparatus as defined in claim 4, in which one drip pan means (38, 39) isaffixed on top of each of said current leads (21, 23) beneath one ofsaid vaporizing means (20, 22).
 6. Vaporizing apparatus as defined inclaim 1, in which an elongated planar glow discharge electrode (24) isprovided disposed edgewise beneath the lowermost of said current returnleads substantially in the same plane as said vaporizing means (20, 22)and said current return leads (21, 23), in which further at least saidlowermost of said current return leads has an end at ground potentialand in which a substantially grounded electrode (25) spaced from andcovering one side of said glow discharge electrode is disposed extendingdownward from said loweRmost current return lead.
 7. Vaporizingapparatus as defined in claim 4, in which baffle means (40) forscreening off said vaporizing means are mounted in such a way as to becapable of being swung into either of two positions, in one of whichsaid baffle means screen off one of said vaporizing means and in theother of said positions said baffle means screen off the other of saidvaporizing means.
 8. Vaporizing apparatus as defined in claim 1, whichsaid current leads (21, 23) mechanically hold in place said vaporizingmeans (20, 22), in which further said vaporizing means are in the formof longitudinal stretched wires (20, 22), in which, further, groundedclamping terminals (35, 36) are electrically connected to saidrespective current return leads (21, 23) for holding one end of eachvaporizing means and in which, further, spring tensioned clampingterminals (33, 34) are provided for the other ends of said vaporizingmeans and are insulatedly supported by said current return leads (21,23) so as to exert tension on said vaporizing means, said springtensioned clamping terminals being connected by flexible conductors (31,32) to a supply voltage source.